Dental syringe with releasable hose coupling

ABSTRACT

A dental syringe provided with a handle having a coupling end and a discharge head for air, water and a spray mist and an electrical heater in the handle. A flexible hose having a coupling end connectable to the coupling end of the handle to supply air, water and electrical current thereto. Coupling means engages with the coupling ends of the handle and hose operable to quickly connect said hose to said handle and automatically connect the conduits and conductors of said hose correspondingly to those in said handle without any disassembly of the syringe. The male coupling body is made of metal and is attached to the flexible hose and has female passages for air and water and for two male electrical conductors, which are surrounded by electrical insulation which extends beyond the end of the coupling body. The female coupling body is made of an electrically insulative material and has male air and water passages and female passages having electrical conductors. When coupled, the insulation around the male electrical conductors extends into the female electrical passages in the female connector.

United States Patent [72] Inventor George H. Stram Hellam,Pa. [21]AppLNo. 678,952 [22] Filed 0ct.30, 1967 [45] Patented Mar. 16,197] [73]Assignee Dentsply International Inc.

York,Pa.

[54] DENTAL SYRINGE WITH RELEASABLE HOSE COUPLING 2 Claims, 6 DrawingFigs.

[52] U.S.Cl l28/173.1, 128/229, 339/16, 339/89, 339/211 [51] Int.Cl....A61c17/02 [50] FieldofSearch l28/173.1, 224 (inquired), 229, 353(Inquired); 339/15, 16, 96,211,111,89

[56] References Cited UNITED STATES PATENTS 455,021 6/1891 Krehbiel339/16 1,936,015 11/1933 Harrell 339/15 2,291,071 7/1942 Bruno.....339/16(C) 2,619,515 11/1952 Doane.... 339/94(M) 2,776,385 1/1957Modrey..... (339/15UX) 3,038,472 6/1962 Gaylord 339/16X 3,254,646 6/1966Stauntetal 128/224 Primary Examiner-George J. Marlo AssistantExaminer-Paul E. Shapiro Attorney-C. Hercus Just ABSTRACT: A dentalsyringe provided with a handle having a coupling end and a dischargehead for air, water and a spray mist and an electrical heater in thehandle. A flexible hose having a coupling end connectable to thecoupling end of the handle to supply air, water and electrical currentthereto. Coupling means engages with the coupling ends of the handle andhose operable to quickly connect said hose to said handle andautomatically connect the conduits and conductors of said hosecorrespondingly to those in said handle without any disassembly of thesyringe. The male coupling body is made of metal and is attached to theflexible hose and has female passages for air and water and for two maleelectrical conductors, which are surrounded by electrical insulationwhich extends beyond the end of the coupling body. The female couplingbody is made of an electrically insulative material and has male air andwater passages and female passages having electrical conductors. Whencoupled, the insulation around the male electrical conductors extendsinto the female electrical passages in the female connector.

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as w s 5 o i 2 ll Patented March 16, 1971 3,570,483

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INVENTOR GEORGE H. STRAM ATTORNEY DENTAL SYRINGE WITH RELEASABLE HOSECOUPLWG CROSS-REFERENCE TO RELATED APPLICATION The present inventionpertains to coupling means by which the coupling end of a dental syringeis connectable to and disconnectable from the coupling end of a hosecontaining air and water conduits and electrical conductors to furnishsuch dental utilities to the syringe for the discharge of air and water,or mixtures thereof in the form of a spray, said nozzle being carried bya discharge head at the opposite end of the handle of the syringe fromthe coupling end thereof. The discharge of either air, water, or a sprayfrom said discharge head is controlled by valve means and actuatingmembers thereon comprising the subject matter of copending applicationSer. No. 658,795, filed Aug. 7, 1967, in the name of the presentinventor.

BACKGROUND OF THE INVENTION For a substantial period of time, dentalsyringes have been available which individually discharge jets of air orwater from nozzle means at one end thereof. These syringes have beenprovided with simple coupling means respectively to connect either anair-conducting or water-conducting hose to coupling means on thesyringe.

In relatively recent years, dental syringes have been available whichare of a compound nature and selectively may be operated to dischargeeither air,.water, or a mixture of the two in the form of a spray mistor the like, depending upon the requirements of any particularintra-oral requirement while treating or operating upon an individualpatient. In order that such discharged streams might not cause anydiscomfort or shock to the patient, heater means also have been providedin the dental stands to which such syringe devices have been connectedfor the supply of such air and water thereto as well as for physicalsupport thereby when the syringe is not in use.

A very limited number of such syringes have also included electricalheating means directly within the body of the syringe and the hose orcord members which are connected to the syringes similarly are providedwith flexible electrical conductors which are arranged in circuit withthe electrical heating means to furnish current thereto. The positioningof air and water conduits and electrical conducting means within suchflexible cords or hoses has presented substantial problems anddifficulty, particularly in regard to interconnecting the conduits andconductors in such cords and hoses to the corresponding passageways,conductors and electrical circuit means in the handles of such syringes.

In view of the foregoing situation, it has been substantially universalpractice to interconnect the conductors and conduits in the cords andhoses to the corresponding means in the handles of the syringes byvarious types of arrangements which, in general, require partial andeven extensive disassembly of at least the handle of the handpiece, forexample, such as by utilizing various means for removing the outer shellwhich usually comprises the actual gripping member of the handle of thesyringe so as to permit access to the various types of connecting meansenclosed within such shell. Effect ing such disconnection, as well asreconnection of such elements usually requires various types of tools,such as screw drivers, pliers or wrenches or special tools to accomplishthe same.

The foregoing problems have also been compounded by the requirement thatthe electrical circuit for electrical heaters within the handle of thesyringe, when provided, must be suitably insulated particularly from themetallic portions and members of the syringe in general. Thus far,rather awkward and complex mechanisms have been resorted to in regard toconnecting the flexible hoses with the body or handle portions ofexisting syringes and, in general, this has resulted largely inmanufacturers requiring the connected syringe and flexible hose beingreturned, intact, to the equipment supplier or factory for servicingwhen any type of repair of the syringe is required.

SUMMARY OF THE INVENTION The principal object of the present inventionis to provide a dental syringe assembly comprising a syringe having ahandle which is provided at one end with a discharge head and theopposite end is the coupling end, said handle also containing anelectric heater arranged to heat the air and water conduit means withinthe handle. The coupling end of the handle is provided with terminalmeansof the air and water conduit means as well as the electric circuitassociated with the electric heater within the handle. A flexibleconduit hose having a coupling end contains a plurality of flexibleconduit means and electrical conductors arranged in compact relationshipand terminal ends thereof and associated with the coupling end of thehose. The coupling ends of said syringe and hose means areinterconnected or disconnected quickly and without the aid of tools bymeans of a preferably threaded and rotatable coupling thirnble carriedby one of the coupling ends and engageable with threaded means on theother coupling end. When the coupling ends of the syringe and hose areconnected by saidcoupling thimble, the air and water conduit means andalso the electrical conductor means respectively therein areautomatically connected in air and watertight relationship, and theelectric circuit for the heater is completed.

Another object of the invention is to provide complementary andinterfltting plug means in association with the coupling ends of thehandle of the syringe and the flexible hose to facilitate theinterconnection of the complementary terminal ends portions of the fluidconduit means and electrical conductor means in said handle and flexiblehose.

It is a further object of the invention to provide simple, inexpensiveelectrical connector elements which are effectively insulated in afoolproof manner so as to permit the same to extend through appropriatepassages in the coupling members of the handle of the syringe and theflexible hose without being short circuited and also being of suchnature so as to permit the use of fluid conduits in the handle of thesyringe and flexible hose. 1

Details of the foregoing objects and other objects of the invention, aswell as details of the invention, are set forth in the followingspecification and illustrated in the accompanying drawing comprising apart thereof.

DESCRIPTION OF THE DRAWING FIG. I is a side elevation of an exemplarysyringe embodying the principles of the present invention, the handlecasing being illustrated in phantom to facilitate the illustration ofother details of the syringe.

FIG. 2 is a fragmentary illustration of the midportion and lower portionof the syringe illustrated in FIG. I as viewed within a plane positionedat to the axis of the syringe as shown in FIG. I.

FIG. 3 is an enlarged bottom plan view of the handle portion of thesyringe shown in FIG. 2, as seen on the line 3-3 of said FIG.

FIG. 4 is an enlarged fragmentary longitudinal sectional view of thecoupling end portion of the syringe shown in FIG. 2, as seen on the line4-4 of said FIG., and the coupling end of the flexible hose beingillustrated in phantom in associatio therewith.

FIG. 5 is a fragmentary, partially longitudinally sectioned view of thecoupling end of a flexible hose arranged to be interconnected to thecoupling end of the syringe shown in FIGS. I, 2 and 4.

FIG. 6 is a longitudinally sectioned view of the coupling element per seof the coupling apparatus of the flexible hose shown in FIG. 5 andillustrating the electrical connectors carried by said coupling elementin insulated relationship thereto.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. I and 2, thesyringe of the present invention comprises a handle III which preferablyis tubular and tip propriately shaped for comfortable accommodationwithin the hand of the user. The same may be formed from any suitablematerial such as metal tubing, molded from appropriate synthetic resin,or otherwise. Connected to one end of the handle is a discharge head 12which may be cast or otherwise molded from any appropriate material suchas metal, synthetic resin or the like. Appropriate screws or pins,complementary screw threads, or otherwise, may be employed to connectthe upper end of handle 10 to the lower portion of the discharge head12. For practical purposes, the head 12 may be considered part of thehandle 10 in that at least portions of the head are normally engaged bythe forefinger and thumb of the user during operation thereof.

Extending laterally from one end of discharge head 12 is a nozzle 14which is arranged to discharge either a stream of air, a stream ofwater, or a spray comprising a mixture of air and water, all of whichexit through the tip 16 and details of which head and nozzle areillustrated in said aforementioned copending application Ser. No.658,795. Similarly, details of valve means contained within thedischarge head 12 are fully described in said copending application, aswell as the manner in which the flnger-engageable members 18 function tooperate said valve means.

The end of the handle 10 opposite that which supports the discharge head12 is referred to as the coupling end and the same supports anexternally threaded coupling member 20 by which the syringe assemblyshown in FIG. 1 is connected to corresponding coupling ends 22 of aflexible tube or hose 24 which is fragmentarily illustrated in FIG. 5.

The coupling member 20 preferably is formed from metal, though, ifdesired, the same may be molded or otherwise formed from synthetic resinor the like. The preferred method for effecting coupling between thecoupling ends of the syringe and the flexible hose is by a couplingmember comprising a rotatable internally threaded coupling thimble 26.Hence, for durability, metal is highly suitable for purposes of formingthe coupling member 20 of the syringe, particularly in view of thepreferably external threads formed thereon in accordance with thepreferred construction.

The coupling member 20 is connected rigidly, such as by solder, to thelower end of the sleeve comprising handle 10 for separative movementrelative to the discharge head 12 and a pair of rigid and preferablymetallic conduit tubes 28 and 30. Said tubes respectively are fixed attheir upper ends to head 12 and are arranged to conduct air and waterbetween the valves therefor, not shown, within the discharge head 12 andthe terminal end of the syringe. The tubes 28 and 30 respectively haveterminal ends 28 and 30' which extend through suitable holes in member20 and into an inwardly directed cylindrical cavity 32 formed in theouter end of coupling member 20 of the syringe, as best illustrated inFIG. 4. Therefore, the coupling member 20 preferably is cup-shaped andsaid holes for tube ends 28' and 30 are formed in the upper end of thecoupling member 20, as viewed in FIGS. 1, 2 and 4, for purposes ofpermitting separative movement of member 20 from said terminal endportions of the conduit tubes 28 and 30 when, for example, theaforementioned screws or pins which detachably secure handle 10 to head12 are removed. Such removal frees the connected handle 10 and member 20for axial movement from the head 12, tubes 28 and 30, and othercomponents normally within handle 10.

The discharge head 12 also is provided with an axially extending recess36 within which a heater element 38 is positioned. In the preferredconstruction, the heater 38 is of the electrical resistance type and maycomprise a metallic resistance coil disposed within an appropriateceramic enclosure, for example. Circuit members comprising insulatedelectrical conductors 40 and 42 are connected in series with theelectrical resistance member, not shown, within the heater element 38.The lower ends of said conductors, as viewed in FIGS. 1 and 2,respectively are electrically connected to socket-type, femaleconnectors 44, which are securely anchored within axially extendingopenings 46 formed within a preferably cylindrical, insulating block 48.The latter may be formed from appropriate synthetic resin or the likeand the lower end thereof, as viewed in FIGS. 1, 2 and 4, preferablyfirmly abuts the inner end of coupling member 20 from which the flange34 extends.

Insulating block 48 also is provided with additional. parallel.longitudinally extending openings 50 through which the conduit tubes 28and 30 extend and within which they preferably are closely fitted so asto assist in operatively positioning the insulating block 48 within theinterior of the tubular handle 10 when the same is mounted in operativeposition and is connected to the discharge head 12 and extends axiallytherefrom. Appropriate cement may be used to position the block 48 infixed position upon conduit tubes 28 and 30.

From FIG. 4 in particular, it will be seen from the foregoingdescription that the terminal end of the syringe, and particularly thecoupling member 20 thereon, is arranged so that the projecting, terminalend portions 28' and 30 of the air and water conduit tubes 28 and 30extend a limited distance away from the innermost end of cylindricalcavity 32 within the coupling member 20. Also, particularly as will beappreciated from FIG. 3, which is an enlarged illustration of theterminal end of the syringe, the outer ends of the openings 46 withinthe insulating block 48 also are coextensive and axially aligned withcorresponding openings 52 in the coupling member 20 and are freelyexposed for the reception of male terminals 54 projecting from thecoupling end 22 of the flexible hose 24. Details of said male terminalsand the coupling end 22 of said tube are as follows.

Referring to FIGS. 5 and 6, it will be seen that the flexible hose 24 isof a composite nature and comprises a pair of flexible, water and airconduit tubes 60 and 62 which, as viewed in FIG. 5, are superimposedupon each other and only one of the same actually is shown, in partiallylongitudinally sectioned manner. A pair of flexible electricalconductors 56 and 58 are provided beside said air and water conduittubes. All of said aforementioned electrical conductors and water andair conduit tubes are arranged in compact parallel relationship witheach other and are covered either with a continuous, flexible rubberlikeor synthetic resin sheath or a braided textile type sheath or covering64. Such arrangement is similar to many types of composite or compoundsupply tubes or hoses used in various kinds of mechanisms, instruments,and the like.

It will be understood that the outer end of the flexible hose 24 whichis not illustrated in the drawing is suitably arranged to be connectedto sources of dental utilities such as supplies of air under pressure,water under pressure such as is available from municipal supplies, andan electric circuit of appropriate capacity to supply current to theheater element 38. The opposite or coupling end ofthe flexible hose 24is provided with an appropriate terminal collar 66 which, for example,preferably is molded from suitable insulating material such as syntheticresin, either of a pliable or rigid nature.

Surrounding the outermost end of said collar 66 is a ferrule 68 ofmetal, for example, which is firmly secured to the collar 66 by anyappropriate means. The outermost end of ferrule 68 has an inwardlyturned flange 70 thereon which engages with a mating, companion flange72 ofa unitary coupling element 74 which, especially for durability,preferably is formed from metal such as brass. This element is shown inFIG. 6 as being unattached to the hose 24 in order that the detailsthereof may be more readily appreciated than in the illustration of FIG.5 wherein the element is shown connected to the terminal end of hose 24.

The outermost end of coupling element 74, as viewed in FIG. 5, comprisesa plug portion 76 which is closely complementary to and is receivedwithin the cylindrical cavity 32 in coupling member 20 of the syringe.Accordingly, the interfitting relation between the plug portion 76 andcavity 32 constitute plug means to facilitate the interconnection ofthese elements and the various interfitting conduit and electricalconductor means respectively carried thereby.

When the flange 70 of the ferrule 68 is interfitted with the flange 2 ofcoupling element 74, said coupling element is fixedly secured withrespect to the terminal collar 66, whereby the element 74 isnonrotatable with respect to the flexible hose 24. Prior to so affixingthe coupling element 74 with respect to terminal collar 66, however, theprojecting ends 78 of the male terminals 54 are suitably connectedelectrically to the terminal ends of the electrical conductors 56 and 58within the flexible hose 24 by any conventional means.

A pair of attaching sleeves 80 and 82 are fixedly connected at one endto a pair of transversely spaced ports 84 and 86 which communicate withcorrespondingly spaced enlarged terminal sockets 88 and 90 whichrespectively closely receive the terminal ends 28' and 30 of conduittubes 28 and 30 which project into the cylindrical cavity 32 of couplingmember 20 of the syringe when the coupling end of flexible tube 24 isconnected thereto. The opposite ends of the attaching sleeves 80 and 82are inserted within the terminal ends of the water and air conduit tubes60 and 62 within the flexible hose 24, as illustrated in exemplarymanner in FIG. 5. The preferably inherent elasticity of the tubes 60 and62 readily effects a tight union between the terminal endsof said tubesand the attaching sleeves 80 and 82.

It is preferably to index the coupling ends of the syringe and flexiblehose 24, especially to insure the desired connections between the waterand air tubes 60 and 62 of flexible hose 24 and the air and water tubes28 and 30 of the syringe. To accomplish this, by reference to FIG, 3, itwill be seen that the terminal ends 28' and 30 of the air and waterconduit tubes 28 and 30 of the syringe are spaced unequal distances fromthe central axis of the coupling end of the syringe. Correspondingly,the the terminal sockets 88 and 90 in coupling element 74 on thecoupling end of the flexible hose 24 are arranged in complementarymanner with respect to the central axis of the preferably cylindricalplug portion 76 of coupling element 74.

One of the very important features of-the present invention which hasmade it possible to utilize very simple coupling means and correspondinginterengageable elements to effect connection between the fluid conduitsand electrical conductors respectively in the flexible hose 24 and thecoupling end of the handle of the syringe comprises the particulararrangement of the male terminals 54, which are carried by the couplingelement 74, and the female connectors 44, which are fixedly supportedwithin the insulating block 48 adjacent the coupling end of the handleof the syringe. The male terminals 54 are sufficiently long that theynot only provide the projecting ends 78 for connection with theelectrical conductors 56 and 58, but especially so as to project anappreciable distance beyond the outer end of the plug portion 76 ofcoupling'element 74.

Especially since the coupling element 74 preferably is formed frommetal, it is necessary that the male terminals 54 be electricallyinsulated therefrom and from each other and this is accomplished quitesimply by the utilization of tubular insulating sleeves 92 which arepreferably tightly complementary to parallel elongated openings 94 whichextend in an axial direction through coupling element 74 for the entirelength thereof. More importantly, as readily can be seen from FIGS. 5and 6, the insulating sleeves 92 extend a substantial distance along theprojecting terminals 54, beyond the outer end of plug portion 76 ofcoupling element 74. Said projecting end portions of the insulatingsleeves 92 are adequate to extend through the full length of theopenings 52 in coupling member in order that the male terminals 54 willnot contact said terminal member which preferably is indicated as beingmade of metal.

As a safety precaution, the length of the projecting end portions of theinsulating sleeves 92 is adequate to extend beyond the outer ends of theopenings 52 in said coupling member 20 and even extend a limiteddistance into openings 46 in the insulating block 46. The outer diameterof the insulating sleeves 92 also is preferably only very slightly lessthan the inner diameter of the openings 52 in coupling member 20 andopenings 46 in insulating block 48.

The slidable projection of the projecting end portions of insulatingsleeves 92 successively through the openings 52 and of insulatingsleeves 92 frictionally within the female connec-' tors 44 so as to beelectrically connected thereto. Such connection serves, therefore, toelectrically connect the conductors 56 and 58 within the flexible hose24 with the electrical conductors 40 and 42 within the handle 10,thereby completing a circuit between the heater element 38 and theconductors 56 and 58 of the hose 24.

At its opposite end, hose 24 is connected to an electric cir-. cuitwhich, incidentally, preferably includes appropriate switch means, notshown, to control the supply of current to and from the heater element38. By way of example, an appropriate master switch of suitable type maybe employed for such purposes, the same being disposed in ON positionduring the time, for example, the dental stand or other supporting meansto which the syringe is attached is disposed in operative. position,such as during the normal office hours of a dentist.

By such an arrangement, the heater 38 is constantly maintained ON duringsuch regular business hours in heating con dition and in view of theimmediate proximity of the heater 38 to the air and water conduit tubes28 and 30 within handle 10, not only the position of the heater withrespect thereto but also the capacity of the heater 38 results in theair and water delivered to the nozzle 14' being heated to a comfortabledegree for discharge into the oral cavity without shock or discomfort tothe patient. In the event any residual air or water within the nozzle 14has cooled from the last use thereof, it is customary technique for adentist to normally discharge such residual portions into a cuspidor orthe like before directing the nozzle 14 into the oral cavity of apatient.

Connection and disconnection of the coupling ends of the syringe andflexible hose 24 is accomplished by means of the clamping thimble 26which is rotatably supported upon the coupling element 74 on thecoupling end of hose 24. The intermediate interior portion between theends of thimble 26 is threaded complementarily to the external threadson coupling member 20 of the syringe and the preferred fit between thethreads is such as to readily permit connection and disconnection simplyby rotation of the thimble 26 manually by an operator. For that purpose,at least a portion of the exterior surface of thimble 26 is suitablyknurled in accordance with conventional practice.

From FIGS. 5 and 6, it will be seen that the coupling element 74 isprovided with a shallow, flat annular groove 96 which rotatably receivesa band 98 which is loosely complementary to the groove 96. The innersurface of one end portion of the thimble 26 is provided with aninwardly projecting, annular rib 100 which is received within acomplementary groove in the outer surface of band 98 so as to permit thethimble 26 to be interlocked therewith and thus become rotatablyconnected to the coupling element 74 but the opposed annular shouldersdefining the opposite sides of the groove 96 provide restricting meanswhich permit only limited .longitudinal movement between thimble 26 andcoupling element 74.

When it is desired to connect the coupling end of flexible hose 24 tothe coupling end of the handle 10 of the syringe, it is only necessary,by use of the means described above, to orient the terminals 54 of theflexible hose 24 with respect to the openings 46 in coupling member 20of the syringe and simultaneously index the terminal ends 28 and 30' ofthe air and water conduit tubes with respect to the terminal sockets 88and 90, which correspond thereto in the coupling element 74 of the hose24. Upon achieving the desired indexed relationship between the couplingends of the syringe and hose, it then is only necessary to rotate thecoupling thimble 26 sufficiently to move the plug portion 76 of couplingelement 74 into plugged relationship with the cylindrical cavity 32 ofcoupling member 20.

When such plugged relationship has been accomplished, the exposed outerends of the terminals 54 will be in firm electrical engagement with themating connectors 44 within the handle of the syringe and the terminalends 28 and 30'lof the air and water conduit tubes 28 and 30 will besnugly received within the terminal sockets 88 and 90 of couplingelement 74. To prevent leakage of air and water between such latterconnections, however, there is provided a compressible sealing gasket102 of suitable thickness disposed within the inner end portion of thecavity 32 in coupling member 28. Said gasket is compressed sufficientlyupon the completion of the plugging relationship of plug portion 76 withcomplementary plugging cavity 32 that the gasket 102 is also firmlycompressed around the exterior surfaces of the terminal encl portions28' and 30 of conduit tubes 28 and 30 that no leakage of either air orwater will occur with respect to the interengaged terminal ends 28, 30'and sockets 88, 90.

Although the structure illustrated in detail and described abovepreferably contemplates that the male terminals 54 be mounted upon thecoupling end of the hose 24 and the female connectors 44 be within thecoupling end of the handle of the syringe, it is to be understood thatthese connectable electrical members may be reversed without departingfrom the spirit of the invention. Similarly, though the coupling thimble26 is illustrated as being rotatably connected to the coupling end ofhose 24 for engagement with the threads of coupling member 20 on thesyringe, it also is to be understood that a reversal of such elementsalso is possible within the purview of the invention, whereby thethimble 26 may be rotatably connected to the coupling end of the handle10 of the syringe, for example.

While the invention has been illustrated and described in its severalpreferred embodiments, it should be understood that the invention is notto be limited to the precise details herein illustrated and describedsince the same may be carried out in other ways falling within the scopeof the invention as claimed.

1 claim:

1. A dental syringe assembly comprising in combination an elongatedhandle means having two ends, a discharge head at one end, an electricheater in said handle means, air and water conduit means in said handlemeans extending from said discharge head to the other end of said handlemeans and terminating thereat, and electrical conductors extending fromsaid heater and terminating at said other end; a flexible conduit hosemeans having an end, electric conductors and air and water conduit meansextending through said hose means and terminating at said conduit end,each of said electrical conductors, air and water conduit means beingconnected respectively to a source of electricity, air and water; afirst coupling end comprising a body, said body being made of metal, airand water passageways extending through said first coupling end body,additional passageways in said coupling end body, electrical connectorsin said additional passageways and extending therethrough beyond theopposite ends of said first coupling end body; a second coupling endcomprising a body, said second coupling end body being formed frominsulation material, air and water passageways in said second couplingend body, electrical connector passageways in said second coupling endbody terminating in electrical connectors complementary to theelectrical connectors in said first coupling end body; coupling meansengageable with the first and second coupling end bodies and operable todetachably connect the same and automatically interconnect thecorresponding air and water passageways and the complementary electricalconnectors in respectively fluidtight and electric current-establishingmanner when said coupling end bodies are connected, said electricalconnectors in said first coupling end body terminating in terminalsprovided with insulation arranged and adapted to extend into saidelectrical connector passageways in said second coupling end body andprevent contact of said terminals with the body of said second couplingend; the air and water passageways and electrical connectors of one ofsaid coupling end bodies being connected respectivel to the terminalends of the air and water conduit means an electrical conductors of saidflexlble' conduit hose, and the air and water passageways and electricalconnectors of the other of said coupling end body being connectedrespectively to the terminal ends of said air and water conduit meansand electrical conductors in said handle means.

2. The dental syringe assembly according to claim 1 in which said secondcoupling end body has a cavity in the outer end means closely fittingwithin said cavity when said coupling end bodies are connected forpurposes of aligning and stabilizing said connection therebetween.

1. A dental syringe assembly comprising in combination an elongatedhandle means having two ends, a discharge head at one end, an electricheater in said handle means, air and water conduit means in said handlemeans extending from said discharge head to the other end of said handlemeans and terminating thereat, and electrical conductors extending fromsaid heater and terminating at said other end; a flexible conduit hosemeans having an end, electric conductors and air and water conduit meansextending through said hose means and terminating at said conduit end,each of said electrical conductors, air and water conduit means beingconnected respectively to a source of electricity, air and water; afirst coupling end comprising a body, said body being made of metal, airand water passageways extending through said first coupling end body,additional passageways in said coupling end body, electrical connectorsin said additional passageways and extending therethrough beyond theopposite ends of said first coupling end body; a second coupling endcomprising a body, said second coupling end body being formed frominsulation material, air and water passageways in said second couplingend body, electrical connector passageways in said second coupling endbody terminating in electrical connectors complementary to theelectrical connectors in said first coupling end body; coupling meansengageable with the first and second coupling end bodies and operable todetachably connect the same and automatically interconnect thecorresponding air and water passageways and the complementary electricalconnectors in respectively fluidtight and electric current-establishingmanner when said coupling end bodies are connected, said electricalconnectors in said first coupling end body terminating in terminalsprovided with insulation arranged and adapted to extend into saidelectrical connector passageways in said second coupling end body andprevent contact of said terminals with the body of said second couplingend; the air and water passageways and electrical connectors of one ofsaid coupling end bodies being connected respectively to the terminalends of the air and water conduit means and electrical conductors ofsaid flexible conduit hose, and the air and water passageways andelectrical connectors of the other of said coupling end body beingconnected respectively to the terminal ends of said air and waterconduit means and electrical conductors in said handle means.
 2. Thedental syringe assembly according to claim 1 in which said secondcoupling end body has a cavity in the outer end means closely fittingwithin said cavity when said coupling end bodies are connected forpurposes of aligning and stabilizing said connection therebetween.